The present invention relates generally to the field of small combustion engines with overhead valve or overhead cam configurations. More specifically the present invention relates to a system for covering rocker arms, valve stems, overhead cams, or other engine components extending from a cylinder head.
Overhead valve (OHV) engines include various components to open and close the intake and exhaust valves. Typically, a camshaft includes cams that push tappets at timed intervals. The tappets are coupled to pushrods, and the pushrods engage rocker arms. The rocker arms pivot upon spherical surfaces of a rocker balls, which are positioned on rocker studs and transfer the upward force of the pushrods into downward force on valve stems, and visa versa. Other rocker arms may pivot upon cylindrical pivots, such as pins, that are secured to a cylinder head without rocker studs. As the rocker arms push down or lift up upon the valve stems, the corresponding intake and exhaust valves open and close in the combustion chamber. Often valve springs are positioned around the valve stems to provide a lifting force to return the rocker arms and valves to the closed position when the cam is no longer engaged with the tappet.
The rocker arms and rocker studs are typically fastened to the top of a cylinder head, with the pushrods and valve stems extending through apertures in the cylinder head. The components of the OHV configuration extending from the top of the cylinder head are typically enclosed by a housing. A head plate forms a bottom portion of the housing. The head plate may be integrally formed with the cylinder head, or may be separately attached to bosses extending from the cylinder head. A rocker cover forms a top portion of the housing, attaching to the head plate and limiting access to the rocker arms and other components of the OHV configuration attached to the top of the cylinder head.